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| 1 /* |
| 2 ** The author disclaims copyright to this source code. |
| 3 ** |
| 4 ************************************************************************* |
| 5 ** Implementation of the "simple" full-text-search tokenizer. |
| 6 */ |
| 7 |
| 8 #include <assert.h> |
| 9 #if !defined(__APPLE__) |
| 10 #include <malloc.h> |
| 11 #else |
| 12 #include <stdlib.h> |
| 13 #endif |
| 14 #include <stdio.h> |
| 15 #include <string.h> |
| 16 #include <ctype.h> |
| 17 |
| 18 #include "tokenizer.h" |
| 19 |
| 20 /* Duplicate a string; the caller must free() the returned string. |
| 21 * (We don't use strdup() since it's not part of the standard C library and |
| 22 * may not be available everywhere.) */ |
| 23 /* TODO(shess) Copied from fulltext.c, consider util.c for such |
| 24 ** things. */ |
| 25 static char *string_dup(const char *s){ |
| 26 char *str = malloc(strlen(s) + 1); |
| 27 strcpy(str, s); |
| 28 return str; |
| 29 } |
| 30 |
| 31 typedef struct simple_tokenizer { |
| 32 sqlite3_tokenizer base; |
| 33 const char *zDelim; /* token delimiters */ |
| 34 } simple_tokenizer; |
| 35 |
| 36 typedef struct simple_tokenizer_cursor { |
| 37 sqlite3_tokenizer_cursor base; |
| 38 const char *pInput; /* input we are tokenizing */ |
| 39 int nBytes; /* size of the input */ |
| 40 const char *pCurrent; /* current position in pInput */ |
| 41 int iToken; /* index of next token to be returned */ |
| 42 char *zToken; /* storage for current token */ |
| 43 int nTokenBytes; /* actual size of current token */ |
| 44 int nTokenAllocated; /* space allocated to zToken buffer */ |
| 45 } simple_tokenizer_cursor; |
| 46 |
| 47 static sqlite3_tokenizer_module simpleTokenizerModule;/* forward declaration */ |
| 48 |
| 49 static int simpleCreate( |
| 50 int argc, const char **argv, |
| 51 sqlite3_tokenizer **ppTokenizer |
| 52 ){ |
| 53 simple_tokenizer *t; |
| 54 |
| 55 t = (simple_tokenizer *) malloc(sizeof(simple_tokenizer)); |
| 56 /* TODO(shess) Delimiters need to remain the same from run to run, |
| 57 ** else we need to reindex. One solution would be a meta-table to |
| 58 ** track such information in the database, then we'd only want this |
| 59 ** information on the initial create. |
| 60 */ |
| 61 if( argc>1 ){ |
| 62 t->zDelim = string_dup(argv[1]); |
| 63 } else { |
| 64 /* Build a string excluding alphanumeric ASCII characters */ |
| 65 char zDelim[0x80]; /* nul-terminated, so nul not a member */ |
| 66 int i, j; |
| 67 for(i=1, j=0; i<0x80; i++){ |
| 68 if( !isalnum(i) ){ |
| 69 zDelim[j++] = i; |
| 70 } |
| 71 } |
| 72 zDelim[j++] = '\0'; |
| 73 assert( j<=sizeof(zDelim) ); |
| 74 t->zDelim = string_dup(zDelim); |
| 75 } |
| 76 |
| 77 *ppTokenizer = &t->base; |
| 78 return SQLITE_OK; |
| 79 } |
| 80 |
| 81 static int simpleDestroy(sqlite3_tokenizer *pTokenizer){ |
| 82 simple_tokenizer *t = (simple_tokenizer *) pTokenizer; |
| 83 |
| 84 free((void *) t->zDelim); |
| 85 free(t); |
| 86 |
| 87 return SQLITE_OK; |
| 88 } |
| 89 |
| 90 static int simpleOpen( |
| 91 sqlite3_tokenizer *pTokenizer, |
| 92 const char *pInput, int nBytes, |
| 93 sqlite3_tokenizer_cursor **ppCursor |
| 94 ){ |
| 95 simple_tokenizer_cursor *c; |
| 96 |
| 97 c = (simple_tokenizer_cursor *) malloc(sizeof(simple_tokenizer_cursor)); |
| 98 c->pInput = pInput; |
| 99 c->nBytes = nBytes<0 ? (int) strlen(pInput) : nBytes; |
| 100 c->pCurrent = c->pInput; /* start tokenizing at the beginning */ |
| 101 c->iToken = 0; |
| 102 c->zToken = NULL; /* no space allocated, yet. */ |
| 103 c->nTokenBytes = 0; |
| 104 c->nTokenAllocated = 0; |
| 105 |
| 106 *ppCursor = &c->base; |
| 107 return SQLITE_OK; |
| 108 } |
| 109 |
| 110 static int simpleClose(sqlite3_tokenizer_cursor *pCursor){ |
| 111 simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; |
| 112 |
| 113 if( NULL!=c->zToken ){ |
| 114 free(c->zToken); |
| 115 } |
| 116 free(c); |
| 117 |
| 118 return SQLITE_OK; |
| 119 } |
| 120 |
| 121 static int simpleNext( |
| 122 sqlite3_tokenizer_cursor *pCursor, |
| 123 const char **ppToken, int *pnBytes, |
| 124 int *piStartOffset, int *piEndOffset, int *piPosition |
| 125 ){ |
| 126 simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor; |
| 127 simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer; |
| 128 int ii; |
| 129 |
| 130 while( c->pCurrent-c->pInput<c->nBytes ){ |
| 131 int n = (int) strcspn(c->pCurrent, t->zDelim); |
| 132 if( n>0 ){ |
| 133 if( n+1>c->nTokenAllocated ){ |
| 134 c->zToken = realloc(c->zToken, n+1); |
| 135 } |
| 136 for(ii=0; ii<n; ii++){ |
| 137 /* TODO(shess) This needs expansion to handle UTF-8 |
| 138 ** case-insensitivity. |
| 139 */ |
| 140 char ch = c->pCurrent[ii]; |
| 141 c->zToken[ii] = (unsigned char)ch<0x80 ? tolower(ch) : ch; |
| 142 } |
| 143 c->zToken[n] = '\0'; |
| 144 *ppToken = c->zToken; |
| 145 *pnBytes = n; |
| 146 *piStartOffset = (int) (c->pCurrent-c->pInput); |
| 147 *piEndOffset = *piStartOffset+n; |
| 148 *piPosition = c->iToken++; |
| 149 c->pCurrent += n + 1; |
| 150 |
| 151 return SQLITE_OK; |
| 152 } |
| 153 c->pCurrent += n + 1; |
| 154 /* TODO(shess) could strspn() to skip delimiters en masse. Needs |
| 155 ** to happen in two places, though, which is annoying. |
| 156 */ |
| 157 } |
| 158 return SQLITE_DONE; |
| 159 } |
| 160 |
| 161 static sqlite3_tokenizer_module simpleTokenizerModule = { |
| 162 0, |
| 163 simpleCreate, |
| 164 simpleDestroy, |
| 165 simpleOpen, |
| 166 simpleClose, |
| 167 simpleNext, |
| 168 }; |
| 169 |
| 170 void get_simple_tokenizer_module( |
| 171 sqlite3_tokenizer_module **ppModule |
| 172 ){ |
| 173 *ppModule = &simpleTokenizerModule; |
| 174 } |
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